/** Extract a class instance from given Type. */ private static Class<?> extractClass(Class<?> ownerClass, Type arg) { if (arg instanceof ParameterizedType) { return extractClass(ownerClass, ((ParameterizedType) arg).getRawType()); } else if (arg instanceof GenericArrayType) { GenericArrayType gat = (GenericArrayType) arg; Type gt = gat.getGenericComponentType(); Class<?> componentClass = extractClass(ownerClass, gt); return Array.newInstance(componentClass, 0).getClass(); } else if (arg instanceof TypeVariable) { TypeVariable<?> tv = (TypeVariable<?>) arg; arg = getTypeVariableMap(ownerClass).get(tv); if (arg == null) { arg = extractBoundForTypeVariable(tv); } else { arg = extractClass(ownerClass, arg); } } return (arg instanceof Class ? (Class<?>) arg : Object.class); }
private static Class<?>[] doResolveTypeArguments( Class<?> ownerClass, Type ifc, Class<?> genericIfc) { if (ifc instanceof ParameterizedType) { ParameterizedType paramIfc = (ParameterizedType) ifc; Type rawType = paramIfc.getRawType(); if (genericIfc.equals(rawType)) { Type[] typeArgs = paramIfc.getActualTypeArguments(); Class<?>[] result = new Class[typeArgs.length]; for (int i = 0; i < typeArgs.length; i++) { Type arg = typeArgs[i]; result[i] = extractClass(ownerClass, arg); } return result; } else if (genericIfc.isAssignableFrom((Class<?>) rawType)) { return doResolveTypeArguments(ownerClass, (Class<?>) rawType, genericIfc); } } else if (ifc != null && genericIfc.isAssignableFrom((Class<?>) ifc)) { return doResolveTypeArguments(ownerClass, (Class<?>) ifc, genericIfc); } return null; }